Non-invasive Early Goal Directed Therapy in Colorectal Surgery: a Feasibility Study

Overview

The Nexfin monitoring system offers a complete non-invasive approach to a continuously estimation of blood pressure, CI and PPV by means of finger-cuff based pulse contour analysis. Several clinical investigations have proven reliability and interchangeability of the Nexfin technology yielding acceptable results especially regarding the trending abilities. At present there is no evidence available, whether a early goal directed hemodynamic optimization protocol based on a completely non-invasive monitoring technology is able to reduce postoperative complication. Therefore, the aim of this single-center study is to compare the clinical outcome and postoperative complications of patients undergoing major colorectal surgery treated with standard of care or with a GDT protocol based on the Nexfin technology.

The Nexfin™ monitoring system is able to provide continuous beat-to-beat stroke volume index (SVI), stroke volume variation (SVV), pulse pressure variation (PPV), cardiac index (CI) and arterial pressure by using an inflatable finger cuff. This system consists of a frequency dependent transfer function for calculation of brachial artery pressure from the finger artery pressure. Major surgery bares the risk of concealed hypoperfusion and therefore possible mismatch in oxygen delivery and oxygen demand. It must be noted, that the "basic" perioperative monitoring, i.e. electrocardiogram, oxygen saturation and non-invasive or invasive blood pressure measurements is not able to accurately detect hypovolemia and ongoing organ hypoperfusion. Perioperatively, patients undergoing major abdominal surgery are prone to high risk of hemodynamic instabilities and consequently relevant changes in oxygen delivery, associated with an increase in postoperative complications and length of stay in hospital. Over the last years several studies focused on early goal directed hemodynamic therapy (GDT) with strong proof for the feasibility of such algorithms and the improvement in patient's outcome with respect to certain clinical scenarios.However, there is still a debate regarding an individualized GDT approach, based on pre-procedural defined individualized hemodynamic goals yielded by an advanced haemodynamic monitoring technology. We do have to distinguish which monitoring system, invasive to non-invasive, matches the kind of estimated risk at what time best.